Congress is advancing a proposal to preempt some California regulations on self-driving cars.

States like California have traditionally regulated how cars are operated, but the federal government regulates their design.

“The trick here is now the vehicles are becoming the operators, so there’s a little blurring of those lines,” says Law Professor Bryant Walker Smith.

He also says the bill would give the National Highway Traffic Safety Administration more authority over autonomous vehicle design. That could preempt current requirements in California for things like an emergency switch to shut off self-driving mode.­

“But that preemption would not preclude states from enacting all manner of other laws related to automated driving,” says Smith.

Registration and insurance would still be left to the state. The Department of Motor Vehicles wouldn’t comment on the bill, which is up for a vote in the U.S. House Energy and Commerce committee this week.